As a consumable electrode arc welding method for welding by feeding a wire in a torch, conventionally, there has been used a consumable single electrode arc welding method for welding by feeding a single wire in a torch. Also, recently, there has been also used a consumable multiple electrode arc welding method for welding by feeding two or more wires in a torch. Especially, in recent years, the consumable multiple electrode arc welding method has been applied to an automatic can manufacturing process, that is, because of its high deposition metal welding, it has been used as one of production efficiency enhancing means. Here, the term “high deposition metal welding” means the welding that forms molten deposition metal with high efficiency.
Also, in these consumable electrode arc welding methods, it is generally known that a weld bead recess called a crater is formed in the welding termination part, which makes it necessary to weld the welding termination part further for filling the crater in. To fill the crater in, in the consumable single electrode arc welding method for welding by feeding a single wire in a torch, the welding termination portion is welded by stopping the torch for a given time at the welding termination position while discharging an arc of a given condition to thereby fill the crater in. On the other hand, in the consumable multiple electrode arc welding method for welding by feeding two or more wires, due to the high molten metal welding thereof, a crater tends to be larger than in the consumable single electrode arc welding method. Because of this, simply by stopping the torch for a given time at the welding termination position for welding the crater, the crater cannot be filled in sufficiently.
Thus, conventionally, for example, in a tandem welding method which is one of consumable multiple electrode arc welding methods, there has been proposed a welding operation to be executed in the welding termination portion for filling such crater in. For instance, according to the JP-A-2002-361413 publication, there is disclosed a method in which, when a welding operation reaches a welding termination position, after the arc generation of a consumable electrode preceding in the welding proceeding direction is terminated, while keeping the arc generation of a consumable electrode following in the welding proceeding direction, the welding operation in the welding proceeding direction is continued for welding the welding termination portion. Also, in the JP-A-2002-361414 publication, when a welding operation reaches a welding termination position, after the arc generation of a consumable electrode following in a welding proceeding direction is terminated, while keeping the arc generation of a consumable electrode preceding in the welding proceeding direction, the torch is moved back in the opposite direction to the welding preceding direction for welding.